Laminate geotextile for soil reinforcement

ABSTRACT

A soil reinforcement geotextile sheet comprising a planar carrier with a plurality of elongate tensile elements mechanically attached in spaced-apart, substantially parallel relation to a major surface of the carrier, for positioning within a soil structure with the tensile elements oriented substantially perpendicular to a sloped face of the soil structure. A method of reinforcing a soil structure is disclosed.

TECHNICAL FIELD

The present invention relates to soil reinforcement geotextiles. More particularly, the present invention relates to geotextile sheets made of a substrate carrier with laminated parallel tensile elements for soil reinforcement.

BACKGROUND OF THE INVENTION

Civil engineering and land site developments often include soil structures including retaining walls that abut earthen back fill; steep slopes; reinforced embankments; landslide repair embankments; sloped canals, lined landfills, and reservoirs; erosion control; coastal protection; foundations; fill over voids; and fill over pile foundations. To resist soil movement, soil reinforcement products are placed within the soil structure. The use of soil reinforcements facilitate easier construction with typically significant cost reductions compared to conventional retaining structures while providing a flexible structure with high load bearing capacity and increased sloped stability by allowing the transfer of tensile forces caused by the weight of the layers of the soil structure.

Soil reinforcements include geosynthetic materials that interact with soil particles to create a composite soil/geosynthetic structure. Because the critical direction of reinforcement is towards a face of the slope, soil reinforcement products typically are made from oriented large molecule polymer materials. One such soil reinforcement product is a grid-sheet made of polymeric materials that are extruded and drawn to align the molecules and yield a high strength to weight ratio. Such grids typically mechanically attach to a retaining wall made of a plurality of blocks and extend laterally into backfill or earthen material for stabilizing the earthen wall and the backfill material. Another type of soil reinforcement product is a sheet made from a non-woven geotextile material with spaced-apart bundles of polyester fibers that are stitched to attach the bundle of fibers to the non-woven geotextile.

While these soil reinforcement products have gained acceptance for reinforcing soil structures, there are drawbacks to their use. Oriented polymeric geogrids are relatively expensive to manufacture compared to a soil reinforcement geotextile sheet. The geogrids are substantially rigid and heavy and as a result, are difficult and awkward to install. Further, the lateral interconnections of such geogrids, while maintaining the parallel spacing of the longitudinal members of the grid, contribute little to the overall effective strength and reinforcement resistance of the geogrid within the soil. In contrast, non-woven geotextile sheets are less expensive but still require a stitching process to attach the bundled polyester fibers.

Accordingly, there is a need in the art for a improved soil reinforcement sheet made of a carrier and attached tensile elements for reinforcement of soil structure. It is to such that the present invention is directed.

SUMMARY OF THE INVENTION

The present invention meets the need in the art for a soil reinforcement sheet for soil structure reinforcement comprising a planar carrier for disposing within a soil structure and a plurality of elongate tensile elements disposed in spaced-apart, substantially parallel relation and attached to a major surface of the carrier.

In another aspect, the present invention provides a method of reinforcing a soil structure, comprising the steps of:

(a) providing a carrier sheet having a major surface that extends substantially planar in a first direction and a second direction and having a minor thickness;

(b) providing a plurality of elongate tensile elements mechanically bonded to the carrier in spaced-apart parallel relation; and

(c) laying the carrier on a surface of soil and overlaying same with additional soil to entrap the carrier therein with the tensile elements in contact with portions of the additional soil, the carrier laid thereon to orient the tensile elements substantially perpendicularly to a face of a slope defined by the additional soil that collects to define a soil structure.

Objects, features, and advantages of the present invention will become apparent upon a reading of the following detailed description with reference to the drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates in perspective view a first embodiment of a soil reinforcement sheet according to the present invention.

FIG. 2 illustrates in cut-away perspective view a soil structure reinforced with the soil reinforcement sheet illustrated in FIG. 2.

FIG. 3 illustrates in perspective view a second embodiment of a soil reinforcement sheet according to the present invention.

DETAILED DESCRIPTION

Referring now in more detail to the drawings, in which like reference numerals indicate like parts, FIG. 1 illustrates in perspective view a soil reinforcement sheet 10 in a first embodiment according to the present invention. The soil reinforcement sheet 10 includes a substantially planar carrier 12 having a major surface 14 and a minor thickness 16. The carrier 12 extends substantially planar in the first direction and a second direction such as an X-Y planar sheet with a relatively thin thickness 16 compared to the distal extents of the major surface 14.

A plurality of elongate tensile elements 18 mechanically attach in spaced-apart, substantially parallel relation to the major surface 14 of the carrier 12. The tensile elements 18 are elongate bands, preferably of a material of high tensile strength. The spaced-apart bands of tensile elements 18 are not interconnected to adjacent ones of the tensile elements. Rather, as illustrated in cut-away view in FIG. 1, the tensile elements 18 mechanically attach to the major surface 14. In the illustrated embodiment, an adhesive 20 attaches the tensile elements 18 to the carrier 12. The tensile elements 18 include an upper surface for contacting soil during installation and use of the soil reinforcement sheet 10, as discussed below. In a preferred embodiment, the tensile elements 18 define a textured surface 22 to facilitate interlocking engagement of the tensile elements with the soil.

The soil reinforcement carrier 12 is an inexpensive fabric material such as a non-woven geotextile formed of randomly laid fibers. The fibers may be continuous or short stable fibers. The non-woven substrate further may be needle punched 24 (see FIG. 1) to form a felt. Other suitable carriers include spunbond fabrics, calendared fabrics, or a woven fabric. The basis weight of the carrier is about 3 ounces per square yard to about 10 ounces per square yard. Suitable non-woven geotextile are PROPEX 4500 SERIES product available from Propex Fabrics, Inc., Austell, Ga.; 100 SERIES EX available from LINQ Industrial Fabrics, Inc., Summerville, S.C.; and GT100 SERIES available from Skaps Industries, Pendergrass, Ga.

The tensile elements 18 are elongated oriented polymeric strapping such as conventionally used for packaging. While such elongated polymeric straps may have smooth surfaces, textured straps provide better interaction with soil during installation and use of the soil reinforcement sheet. An adhesive such as a hot melt glue, pressure activated adhesive or other suitable bonding material, attaches the tensile elements 18 or straps to the non-woven substrate carrier 10. Suitable elongate straps are available from U.S. Strapping Co., Inc., Lancaster, S.C. and Signode Packaging Systems, Glenview, Ill.

FIG. 2 illustrates in cut-away perspective view an earthen bank or soil structure 30 reinforced with a plurality of spaced apart soil reinforcement sheets 10 positioned within the earthen bank. The soil structure 30 defines a slope face 32. It is to be appreciated that the slope face may be an embankment or a wall of the soil structure. The soil reinforcement sheets 10 are disposed within the soil structure 30 with the tensile elements 18 aligned substantially perpendicular to the slope face 32. Thus, a longitudinal axis of the tensile element 18 is oriented substantially horizontally perpendicular to a transverse plane 36 of the slope face 32. Additional soil 34 overlies the soil reinforcement sheet 10 and contactingly engages the tensile elements 18.

FIG. 3 illustrates in perspective view a second embodiment of a soil reinforcement sheet 40 in which the tensile elements 18 mechanically attach to the carrier by a stitching 42. The stitching 42 provides a yarn or fiber that overlies the tensile element 18 and mechanically attaches through the carrier 12.

With reference to FIG. 2, the soil structure 30 with the slope face 32 is stabilized with one or more layers of soil reinforcement sheets 10. The soil reinforcement sheets 10 are laid on a ground surface during construction of the soil structure 30. An edge of the soil reinforcement sheet 10 is disposed near the slope face 32 and the sheet 10 extends substantially horizontally planarly over the area for forming the soil structure 30. The soil reinforcement sheet 10 is oriented with the tensile elements perpendicular to the slope face 32. Additional soil 34 deposited over the soil reinforcement sheet 10 entraps the soil reinforcement sheet within the soil structure 30. The additional soil interacts with the tensile elements 18, and particularly the textured surface 22, to further secure the soil reinforcement sheet within the earthen bank. Additional soil reinforcement sheets 10 are positioned in the earthen bank 30 in spaced-apart relation, in like manner until the soil structure 30 is complete.

The soil reinforcement sheet 10 provides a plurality of aligned tensile elements 18 that operate in concerted and simultaneous fashion to resist soil movement within the soil structure. The soil reinforcement sheet 10 provides an integral structure with dimensional stability for resisting movement of soil structures. The carrier 12 provides a light-weight yet dimensionally stable planar sheet for readily orienting the tensile elements 18 in spaced-apart relation perpendicular to the slope face 32 of the soil structure 30. Installation of the soil reinforcement sheet 10 according to the present invention is readily accomplished with reduced manpower and labor while the material costs are significantly less then prior geogrids and geotextiles by use of an efficient geotextile carrier and inexpensive yet high strength tensile elements or straps.

The present invention accordingly provides the soil reinforcement sheet made of the carrier for positioning the tensile elements in the oriented relation within soil structures. The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. The invention is not to be construed as limited to the particular forms disclosed as these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departing from the spirit of the invention described in the following claims. 

1. A soil reinforcement sheet for soil structures, comprising a planar carrier and a plurality of elongate tensile elements disposed in spaced-apart, substantially parallel relation and attached to a major surface of the carrier for disposing as a reinforcement within a soil structure.
 2. The soil reinforcement sheet as recited in claim 1, wherein the carrier is a nonwoven substrate.
 3. The soil reinforcement sheet as recited in claim 1, wherein the carrier has a weight of about 3 ounces per square yard to about 10 ounces per square yard.
 4. The soil reinforcement sheet as recited in claim 1, wherein the carrier is a needle punched fabric.
 5. The soil reinforcement sheet as recited in claim 1, wherein the carrier is a spunbond fabric.
 6. The soil reinforcement sheet as recited in claim 1, wherein the carrier is a calendared fabric.
 7. The soil reinforcement sheet as recited in claim 1, further comprising an adhesive layer to attach the tensile elements to the major surface of the carrier.
 8. The soil reinforcement sheet as recited in claim 7, wherein the adhesive layer comprises a heat activated polymeric.
 9. The soil reinforcement sheet as recited in claim 1, wherein an upper surface of the tensile elements is textured.
 10. The soil reinforcement sheet as recited in claim 1, wherein the carrier comprises a plurality of continuous fibers interlaid together to define a nonwoven sheet.
 11. The soil reinforcement sheet as recited in claim 1, wherein the carrier comprises a plurality of staple fibers needled together to define a felt sheet.
 12. The soil reinforcement sheet as recited in claim 1, wherein the tensile elements attach to the carrier with a mechanical attachment.
 13. The soil reinforcement sheet as recited in claim 12, wherein the mechanical attachment of the tensile elements to the carrier comprises a stitching with a yarn.
 14. The soil reinforcement sheet as recited in claim 12, wherein the mechanical attachment of the tensile elements to the carrier comprises an adhesive.
 15. A soil reinforcement composite comprising a nonwoven fabric carrier and a plurality of elongate tensile elements mechanically attached in spaced-apart, substantially parallel relation to a major surface of the carrier.
 16. The soil reinforcement composite as recited in claim 15, wherein the carrier has a weight of about 3 ounces per square yard to about 10 ounces per square yard.
 17. The soil reinforcement composite as recited in claim 15, wherein the carrier is a needle punched fabric.
 18. The soil reinforcement composite as recited in claim 15, wherein the carrier is a spunbond fabric.
 19. The soil reinforcement composite as recited in claim 15, wherein the carrier is a calendared fabric.
 20. The soil reinforcement composite as recited in claim 15, wherein an upper surface of the each of the tensile elements is textured.
 21. The soil reinforcement composite as recited in claim 15, wherein the carrier comprises a plurality of continuous fibers interlaid together.
 22. The soil reinforcement composite as recited in claim 15, wherein the carrier comprises a plurality of staple fibers needled together to define a felt sheet.
 23. The soil reinforcement composite as recited in claim 15, wherein the mechanical attachment of the tensile elements to the carrier comprises a stitching with a yarn.
 24. The soil reinforcement composite as recited in claim 15, wherein the mechanical attachment of the tensile elements to the carrier comprises an adhesive.
 25. A method of reinforcing a soil structure comprising the steps of: (a) providing a carrier sheet having a major surface that extends substantially planar in a first direction and a second direction and having a minor thickness; (b) providing a plurality of elongate tensile elements mechanically bonded to the carrier in spaced-apart parallel relation; and (c) laying the carrier on a surface of soil and overlaying same with additional soil to entrap the carrier therein with the tensile elements in contact with portions of the additional soil, the carrier laid thereon to orient the tensile elements substantially perpendicular to a face of a slope of the soil structure.
 26. The method as recited in claim 25, wherein the carrier comprises a nonwoven fabric.
 27. The method as recited in claim 25, further comprising the step of needling the carrier to define a felt sheet.
 28. The method as recited in claim 25, wherein the tensile elements mechanically attach to the carrier by a step of adhering with an adhesive.
 29. The method as recited in claim 25, wherein the tensile elements mechanically attach to the carrier by a step of stitching a yarn over the tensile element.
 30. The method as recited in claim 25, wherein the carrier has a basis weight of about 3 ounces per square yard to about 10 ounces per square yard. 